The 3 drains are 1 1/2″ black PVC and the 2 returns are 1″ black PVC. The drain method used is known as the “Bean Animal”, named after the forum handle of the reefer that perfected the design. It consists of three drains, the one on the right (1) with a gate valve is a full siphon, meaning that is is adjusted to a point where no air is being drawn in with the water. The center drain (2), or clear channel has a small air vent installed on the top of the standpipe above it, allowing a small amount of excess water to drain without drawing much air into the water stream. The left drain (3) is an emergency overflow. It is installed so that it will handle all the water if necessary because of a blockage on the other two drains.
The left emergency overflow is open on the top while the other two look very much like a typical durso, except that the full siphon on the right has no air hole.
The airline tubing is fastened just above the water level so that if the water rises in the overflow box it will draw water and become a full siphon which handles much more volume. I will update this post later with some photos of the standpipes out of the tank.
Installing the bulkheads presented a challenge when it came to tightening the bulkhead nuts. With 1 1/2″ of foam and plywood between the tank bottom and the 1/4″ steel of the stand, it became impossible to tighten the nuts with regular tools.
After some filing and a little bit of help from Iggy and his welder, I now have two wrenches that will allow me to tighten or adjust the bulkhead nuts.
With the pump running, there are no bubbles being released into the sump. No air also means no noise.
The return pump is a Water Blaster HY-7000 by Reef Octopus. It is rated 88 watts 97% efficiency Max Flow=1800gph Max Head=12ft. Very quiet.